The purpose of this project is to determine the pathway and regulation of AMP catabolism in several prokaryotic and simple eukaryotic organisms. Previous experiments have indicated that AMP nucleosidase is the regulatory enzyme in bacteria while one simple eukaryote, bakers yeast, contains activity which catalyzes the deamination of AMP. In vivo experiments with E. coli will attempt to correlate changes in total adenylate pool size with the activity of AMP nucleosidase and with the appearance of products of the reaction. Changes in adenylate pool size will be initiated by aerobic-anaerobic transitions in growing cultures. Experiments with bakers yeast will be directed at the isolation and characterization of the AMP deaminase activity. BIBLIOGRAPHIC REFERENCES: "The Mechanism of Phosphoenolpyruvate Carboxykinase Inhibition by 3 Mercaptopicolinic Acid" M. Jomain-Baum, V.L. Schramm and R.W. Hanson, J. Biol. Chem. 251, 37-44, 1976. "Comparison of Initial Velocity and Binding Data for Allosteric Adenosine Monophosphate Nucleosidase" Schramm, V.L., J. Biol. Chem. 251, 3417-3424, 1976.